The present invention relates to a unitary compressor assembly, in which a compressor and its external-rotor drive motor are arranged in a housing on the same stationary shaft and in which a friction pump for lubricating the compressor is provided at the end of the stationary shaft away from the compressor. The outlet of the pump leads into a canal drilled in the stationary shaft, and inlet of the pump extends into the lubricant supply at the bottom of the unitary housing. The pump also has a hollow cylinder coupled to the external rotor; the cylinder serves as the pump's impeller.
Such a compressor unit is described in DE No.-A1-15 03 408, where the friction pump is formed by the bearing sleeve, which is designed as a hollow cylinder; spiral slots are provided in the stationary shaft in the region of the bearing sleeve. While such a friction pump is of very simple design, it can pump only a small amount of oil.
DE No.-A1-24 28 932 shows a friction pump having a shaft which rotates, as the impeller, in a hollow cylinder. Between the shaft and the hollow cylinder there is a gap in which the medium to be transported is dragged along by the rotating shaft. The gap extends over part of the circumference of the hollow cylinder and is confined on both sides by an interrupter which narrows the gap. The entrance and exit for the medium to be pumped are provided at the beginning and the end of the gap. In order to increase the output, several gaps are provided around the circumference of the hollow cylinder. While the pumped volume can be increased in this manner, the output pressure drops substantially because of the shortening of the length of the individual gaps.
DE No.-B2-27 10 734 corresponds to British Pat. No. 1,566,687 and describes a compressor unit with a radial piston compressor in which oil is introduced into gaps existing between the pistons and the walls of the piston spaces as well as into the gap existing between the cylinder block and the stationary shaft. For this purpose a relatively large quantity of oil with an adequate pumping pressure is required.
It is an object of the invention to develop a compressor unit of the type described at the outset in which oil necessary for lubricating and sealing the mutually movable parts of the compressor is pumped in sufficient quantity and also with the required pressure.